I am not Erik, but I will venture that this design is aimed at making the most compact multiple shot rifle or shotgun. The same could be done with a single, I guess. This thing even with ful length barrels is shorter ready to shoot than many takedowns when broken down.

This inventive design is not patently flawed, but it is not at all what is in the minds eye when thinking of double rifles. A special purpose tool not a fine sporting arm.